Make checking luggage much faster/easier and at the destination get it out for pick up much faster than is done now. Dramatically shrink or remove the overhead bins. Boarding and security line problems solved.
No matter how efficient they get at checking bags, though, not having to do it will always be faster.
I don't really see how much faster they can get in terms of unloading the bags... you will still have to wait for all the bags to come out on the conveyer belt, and whoever gets the last bag will have to wait quite a bit.
This is what causes at least 50% of queues. Everyone can take 1 small bag. Nothing on wheels. If you can't lift it above your head it's too heavy. No exceptions. Overhead bins will be sufficient, no hunting around for a space, easier to get your bag at the end of a journey.
On the other hand; I have taken a 35 liter backpack on many trips. No waiting at the carousel to get my suitcase; just walk straight out of the airport.